Conveying devices in the sense of the invention, which can also be termed transport devices, are escalators and moving walkways with a plurality of tread units, i.e. steps or moving walkway plates, which are connected to form an endless conveyor. Users of the conveying devices stand on the tread surfaces of the tread units or walk on the tread units in the same direction of movement as the conveying devices move or progress.
In the case of escalators, the tread units form escalator steps, hereinafter termed steps, and in the case of moving walkways the tread units form moving walkway plates, hereinafter termed plates. Escalators bridge, with a relatively large angle of inclination, greater distances in height such as entire storeys. Thereagainst, moving walkways run horizontally or at a slight inclination, but in general with smaller angles of inclination than escalators.
Typically, such conveying devices comprise drive runs constructed as step chains or plate chains. For the sake of simplicity merely drive runs are discussed in the following. These drive runs are driven in order to move the steps or plates in transport direction and, in accordance with the state of the art, they are provided at uniform spacings with so-termed step rollers or plate rollers (guide rollers, chain rollers). These guide rollers move or roll along dedicated or provided guide rails. In the region of the ends of the conveying devices the drive trains run, by the guide rollers, around deflecting wheels (or chain wheels) and thus execute a change in direction. Slide elements can also be used instead of drag rollers. The slide elements or the rollable elements (guide rollers) are directly fastened to a step chain or plate chain serving as drive run, as described further above.
In addition to the step chains or plate chains inclusive of the slide elements or rollable elements fastened thereto two further rollers, which are termed drag rollers and roll along separate guide rails, are required for each step or plate.
The steps or plates have in the past been relatively complicated to produce or cast and also expensive, since they have to be intrinsically very stable and torsionally stiff. Moreover, the steps or plates have to be made with a high degree of accuracy in order to guarantee safe, quite and jerk-free running. An essential element of each step or each plate is the step support or plate support, which has a solid, essentially load-bearing function. The support has to be very stable, strong, torsionally stiff and light, which leads to a high level of material outlay or material consumption and processing costs as well as die-casting production costs.
Various proposals have already been made with regard to how the weight of the step support or plate support can be reduced.
In DE 2051802 A1 it is proposed to produce the step support from foamed plastics material. This is indeed light, but not stable and also not durable in the long term.
According to GB 2216825 the plate support consists of a frame of four metal angle irons, within which three angle strips are provided. Provided for steps are only the three angle strips together with two step cheeks. These metal angle irons or metal strips are thick and thus heavy.
In addition, according to JP 08-245152 A two cross members in the form of solid metal angle irons, which co-operate with step cheeks, are provided as step support.
DD 69443 relates to a step for escalators in which side cheeks are integrally connected with a front part. The front part is then covered by a riser element. A tread plate serving as support for a tread element rests on this angled element. Overall, a very much more solid plate is thus employed here.
Finally, a support consisting of solid metal angle irons is also described in JP 10-45365.
The wish exists, particularly for more economic initial equipping of conveying devices, to replace the steps and plates by improved components without in that case, however, impairing running smoothness, travel characteristics, stability, robustness and reliability as well as stability. Moreover, the production process shall be simplified and accelerated. Beyond that, there shall be no increase in weight, so as not to thereby prejudice running characteristics.